The objective of this research is to analyze sera from normal subjects and patients with various types of neoplastic diseases in order to identify biological markers which can be used to detect cancer at the earliest possible development. With the reversed phase mode of high pressure liquid chromatography, serum nucleosides and bases, including the methylated compounds, and uric acid can be analyzed reliably, rapidly, (1/2 hr.) and sensitively (picomole range). Specifically our objectives are: (1) To determine baseline concerntrations for the nucleosides and bases found in the cold soluble acid extracts of sera from normal subjects who have no known medical problems, (2) To establish a range of normal values, (3) To analyze sera from a large number of patients with various types of neoplastic diseases and a limited number from patients with other types of diseases, (4) To identify and quantify the nucleosides and bases which are outside the normal range and those not present in serum profiles of normal subjects, (5) To correlate the changes observed with the clinical data, and (6) To analyze our data to determine if the differences that exist in serum profiles of patients with cancer are statistically valid.